staging: vchiq_arm: Add a matching unregister call

All the registered children of vchiq have a corresponding call to
platform_device_unregister except bcm2835_audio. Fix that.

Fixes: 25c7597a ("staging: vchiq_arm: Register a platform device for audio")
Signed-off-by: Phil Elwell <phil@raspberrypi.com>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Link: https://lore.kernel.org/r/20200629150945.10720-9-nsaenzjulienne@suse.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c

@@ -2805,6 +2805,7 @@ static int vchiq_probe(struct platform_device *pdev)
 
 static int vchiq_remove(struct platform_device *pdev)
 {
+	platform_device_unregister(bcm2835_audio);
 	platform_device_unregister(bcm2835_camera);
 	vchiq_debugfs_deinit();
 	device_destroy(vchiq_class, vchiq_devid);